hurry! how can I clone large DNA fragment - noboday answer? (Apr/13/2006 )

hi there: can someone give me a good suggestion about cloning large DNA fragment (about 32kb) in comsid to another vector. it usaully low effiency for cloning.

I am not familiar with comsid system in fact, while I still have a suggestion: After digestion, use digestion product directly to ligation reaction with anther vector which digested by the same RE and dephosphorated, it is better that the anther vector using different selection to guarantee elimination of the growth of cosmid clone.

I have experiences with cloning larger fragments from lambda clone (screened from genomic DNA library). And using the same strategy, I have clone my interested fragments from lambda clone DNA to SK vector, one of such fragment is >20kb.